Known animal feed additives include probiotic products for oral administration, either specifically or by inclusion in feed, and consist of fermented cultures of non-pathogenic bacteria, typically lactobacilli and/or streptococci.
Probiotics are used to improve rate of growth and feed conversion efficiency in young animals and to reduce incidence of enteritis and diarrhoea. However, the effects of such products are highly variable.
The essential mode of action of probiotics is not, in fact, understood. It is commonly thought that they enhance the numbers of non-pathogenic bacteria in the gut, which may assist digestion, possibly through enzyme production, and also increase competition with populations of potentially harmful bacteria such as Escherichia coli. However, this is not proved. In fact, the normal dosage of a probiotic is usually insufficient to add appreciably to the intestinal population and this casts doubt on the commonly believed mode of action referred to.
Most importantly, since the mode of action is not in fact sufficiently understood, meaningful quality control of probiotic products is virtually impossible.
A principal object of this invention is to provide an animal feed additive and economical method of manufacture thereof based on improved knowledge of the source of the beneficial effects of cultures of non-pathogenic bacteria. This permits meaningful assay and hence meaningful quality control.